This invention relates to two improved brass alloys and their fabrication process, and in particular to a ternary silicon brass alloy which is fabricated into strip, sheet, or wire. One of the new alloys, a beta brass alloy, has a low spring back coefficient and a shape memory effect.
Utilization of various report elements in a brass (copper-zinc) system has been suggested heretofore for the purpose of obtaining certain desired characteristics in the system. Edmunds in U.S. Pat. No. 2,394,673, for example, suggested the addition of 1.2% silicon to a 70/30 cartridge brass to provide resistance to season cracking. The present inventor has investigated numerous ternary beta brass alloys and has reported his findings in the Transactions of the Metallurgical Society of AIME, Volume 230 (1964), Page 267; Volume 230, Page 1662 (1964); Volume 236, Page 1532 (1966); Volume 239, Page 756; Volume 239, Page 1668 (1967); and Metallurgical Transactions, Volume 1, Page 251 (1970).
These cited references reported studies relating to the Martensitic transformations of various ternary brass alloys. A determination was made of the Martensitic transformation temperature as a function of the percentage of the third element content in such alloys. In addition, an investigation of the reaction of such alloys to stresses and temperature changes were reported in these various publications. These publications thus serve as a part of the background to the invention for the beta brass alloy.
Additional background information relates to the formability of multiphase copper based alloys (such as Muntz Metal, 60 Cu - 40 Zn). Such alloys are not usually cold formed. In fact, the Metals Handbook reports that some compositions are impossible to cold work enough to produce spring temper, a reduction in thickness of 60%. Since these two-phase materials have poor cold forming and drawing properties compared with single phase alloys, the castings are usually broken down by hot-working. To overcome such difficulties and processing requirements, the described alpha plus beta brass alloy and process was developed.